The text limit is a limitation of the original network, not some artificial limit that Apple has placed upon it. Originally, text messages were a bonus extra because someone had a bright idea about what to do with surplus data packets on the network. Or something.Yeah, the whole SMS thing is artificially enforced. You can get unlimited YouTube videos, but tiny 100 char text messages are limited.
So, yeah, I have to assume AT&T won't be behind Apple allowing their subscribers to skip over them.
But they probably didn't think that texting would be as popular as it is (particularly in the UK - I know Americans are generally less enthused with this method of mobile communication)
However, texting is still a massive revenue stream and I can't see it being by-passed. Thanks God (in some ways) that Apple hasn't gone down the MMS route, as that would potentially mean artificial limitations on sending photos in emails, etc.